This is WEEKEND EDITION from NPR News. I'm Linda Wertheimer. The U.S. military continued airstrikes yesterday in northern Iraq. The strikes are meant to defend the Yazidi religious minority which has been under attack from Islamic state militants. American aircraft also dropped food and water to thousands of Yazidis stranded on the Sinjar mountain along the Iraq-Syria border. This morning we spoke to Nickolay Mladenov, the United Nations Special Envoy to Iraq. He described the situation in northern Iraq.

NICKOLAY MLADENOV: It is dire. It is very, very serious. We're continuing to face a massive humanitarian crisis with hundreds of thousands of people who have been displaced by the latest takeover of areas by the Islamic state. And I believe that we are facing a situation in which we can say that had it not been for the U.S. airdrops that started two days ago, we would really be facing genocide of some communities that been there for thousands of years.

WERTHEIMER: For more on the tense situation on Mount Sinjar in the north of Iraq, I'm joined by Alissa Rubin, the New York Times reporter who is there. Alissa, thank you very much for talking with us.

ALISSA RUBIN: Thank you.

WERTHEIMER: What is the latest this morning about the Yazidis on Mount Sinjar? What do you know about whether these airdrops have had any effect?

RUBIN: They have an effect on the people whom the food reaches, but the mountain is very large. And there are Yazidis spread across the - it seems like almost the entire mountain. So it's difficult for the airdrops to reach everyone.

So when I interview people, I always ask them if they received any food or water from the airdrops. And many of them never saw it. They heard about it. They occasionally saw people walking by who had received some, but not all the people have received it.

One of the questions that is very difficult to answer is how many people are on the mountain? The estimates we've heard from American officials is they believe between 5,000 and 12,000 which gives the - if they're that far apart, those two numbers, you can tell that people don't really have a strong idea. I think that the scale of this disaster is really larger than people may have fully taken on initially.

WERTHEIMER: You mean the humanitarian disaster?

RUBIN: Humanitarian, yes. Yes, they - I mean, the numbers of people, their declining condition, the ability of people to walk - I mean, we're seeing people sometimes half carried across. They're in really straitened circumstances.

WERTHEIMER: Can you tell whether the military airstrikes have had any effect in the attempt to both prevent the Islamic state forces from getting to Erbil and make the people on the mountain safe?

RUBIN: I would say on defending Erbil, yes, it does seem to have had some impact. The strikes seem to have halted the Islamic state efforts to advance towards Erbil. And just a few minutes ago, we were talking to people in the Peshmerga who said that they had regained the other village or town that had been taken earlier in the week also within the Kurdish borders. And that that was back in Kurdish hands. So yes, I think it's had an impact there.

On the mountain, which is on the far west of the country, it's had the effect of killing some of the Islamic state fighters who are on the mountain and appear to be beginning to pursue the Yazidis onto the mountain. But it's not clear that it had a really appreciable impact. There's a lot of Islamic state fighters in the Sinjar area. And it would take a long time to really make a big difference there.

WERTHEIMER: Alissa Rubin is the New York Times reporter in northern Iraq. Alissa, thank you very much for this.